The present invention relates to compact optical amplifiers.
Optical communication systems based on glass optical fibers (GOF) allow communication signals to be transmitted not only over long distances with low attenuation, but also at extremely high data rates, or bandwidth capacity. This capability arises from the propagation of a single optical signal mode in the low-loss windows of glass located at the near-infrared wavelengths of 850, 1310, and 1550 nm. Since the introduction of erbium-doped fiber amplifiers (EDFAs), the last decade has witnessed the emergence of single-mode GOF as the standard data transmission medium for wide area networks (WANs), especially in terrestrial and transoceanic communication backbones. In addition, the bandwidth performance of single-mode GOF has been vastly enhanced by the development of dense wavelength division multiplexing (DWDM), which can couple up to 40 channels of different wavelengths of light into a single fiber, with each channel carrying up to 10 gigabits of data per second. Moreover, recently, a signal transmission of 1 terabit (1012 bits) per second has been achieved over a single fiber on a 100-channel DWDM system. Bandwidth capacities are increasing at rates of as much as an order of magnitude per year.
The success of the single-mode GOF in long-haul communication backbones has given rise to the new technology of optical networking. The universal objective is to integrate voice video, and data streams over all-optical systems as communication signals make their way from WANs down to smaller local area networks (LANs) of Metro and Access networks, down to the curb (FTTC), home (FTTH), and finally arriving to the end user by fiber to the desktop (FTTD). Examples are the recent explosion of the Internet and use of the World Wide Web, which are demanding vastly higher bandwidth performance in short- and medium-distance applications. Yet, as the optical network nears the end user starting at the LAN stage, the network is characterized by numerous splittings of the input signal into many channels. This feature represents a fundamental problem for optical networks. Each time the input signal is split, the signal strength per channel is naturally reduced.
Rare earth doped optical amplifiers are emerging as the predominant optical signal amplification device for every aspect of optical communication networks spanning from repeaters, pre-amplifiers, and power boosters to wavelength division multiplexed (WDM) systems. These amplifiers are suitable for long-haul, submarine, metro, community antenna television (CATV) and local area networks. An optical amplifier amplifies an optical signal directly in the optical domain without converting the signal into an electrical signal and reconverting the electrical signal back to an optical signal. As optical telecommunication networks push further and further toward the end user, as represented by the technology of FTTC, FTTH, and FTTD, there is an ever growing demand for compact and low cost optical amplification devices.
Current fiber optics architectures utilize highly expensive, bulky EDFA modules based on costly electronic and photonic bulk components that require tedious alignment and connections. Known packaged optical amplifier assemblies include a number of commercially available optical components, such as optical isolators, erbium doped optical fibers, wavelength division multiplexing couplers, tap couplers, etc., which are fusion spliced together to form the optical part of an optical amplifier module. The electronics driving circuitry part of the optical amplifier is built on a separate platform, typically on a printed circuit board. The electronics board and the optical part are separate and are located in two different parts of the amplifier module. Such a multi-layer approach is suitable for complicated, multi-stage amplifiers used in long-haul optical communication systems. However, as an optical network nears the local area level, due to vast signal splitting, a more compact, low-cost, and easy to manufacture approach is needed.
It would be beneficial to provide a highly efficient, compact optical amplifier module that is designed and built utilizing integrated printed circuit board components. Such a module will provide a cost-effective, compact solution to the problem of signal reduction from splitting because the module will utilize reduced space, weight, size, and power consumption natural to integrated compact architectures.
Briefly, the present invention provides an optical amplifier module. The optical amplifier module comprises a housing having an interior length and an interior width generally shorter than the interior length and an electronic control board disposed within the housing. The electronic control board includes a plurality of electronically connected components. The optical amplifier module further comprises a gain medium disposed in the housing in a generally circularly spiral shape, such that the gain medium has a radius of curvature approximately one half the interior width of the housing. The optical amplifier further comprises a pump laser electronically connected to the electronic control board and optically connected to the gain medium.